A metal alloy for making a dental restoration must be strong, tough, resistant to tarnish, oxidation and corrosion, compatible with the human oral environment (biocompatible), have good castability and, if used with porcelain, have a suitable coefficient of thermal expansion to be fusible to porcelain.
Effective dental alloys can be divided into two groups depending upon whether or not they contain precious metals. Those containing such metals are relatively expensive because of their high precious metal content. Nonprecious alloys are generally inferior in handling characteristics to precious alloys, usually having an undesirably high (230-320 BHN) hardness, and are generally relatively hard to cast, grind, or otherwise finish. In addition, when using such alloys it is frequently hard to produce castings giving a good fit to a metal die. An object of this invention is to provide a highly effective and relatively simple and economical nonprecious alloy suitable for dental use including fusibility to porcelain.